How to use array_column function in php

array_column(array, column_name) is another very powerful function available in PHP. It allows to extract all the values from the specified column from a multi-dimensional array without looping into each one of the nested arrays. These are the most common ways to implement this function:

Option 1. With a multi-dimensional array:

$persons = [
    [
        'id' => 50001,
        'first_name' => 'John',
        'last_name' => 'Doe',
    ],
    [
        'id' => 31245,
        'first_name' => 'Sally',
        'last_name' => 'Smith',
    ],
    [
        'id' => 53642,
        'first_name' => 'Jane',
        'last_name' => 'Jones',
    ],
    [
        'id' => 56213,
        'first_name' => 'Peter',
        'last_name' => 'Doe',
    ]
];

$result = array_column($persons, 'last_name');

This will output:

Array
(
    [0] => Doe
    [1] => Smith
    [2] => Jones
    [3] => Doe
)

 Option 2. Specify a key from the nested arrays as the key for each one of the values extracted:

$persons = [
    [
        'id' => 50001,
        'first_name' => 'John',
        'last_name' => 'Doe',
    ],
    [
        'id' => 31245,
        'first_name' => 'Sally',
        'last_name' => 'Smith',
    ],
    [
        'id' => 53642,
        'first_name' => 'Jane',
        'last_name' => 'Jones',
    ],
    [
        'id' => 56213,
        'first_name' => 'Peter',
        'last_name' => 'Doe',
    ]
];

$result = array_column($persons, 'last_name' , 'id');

This will output:

Array
(
    [50001] => Doe
    [31245] => Smith
    [53642] => Jones
    [56213] => Doe
)

Option 3. Get the values of a given property in a array of DTOs (refer to Using DTOs in PHP Symfony, How to validate input data in Symfony using DTOs for more info on these data structures):

class userDto
{
    /**
     * @var int
     */
    public int $id;
    
    /**
     * @var string
     */
    public string $firstName;
    
    /**
     * @var string
     */
    public string $lastName;
}

$user_1 = new userDto();
$user_1->id = 101010;
$user_1->firstName ='Sally';
$user_1->lastName = 'Smith';

$user_2 = new userDto();
$user_2->id = 202020;
$user_2->firstName ='John';
$user_2->lastName = 'Doe';

$user_3 = new userDto();
$user_3->id = 303030;
$user_3->firstName ='Peter';
$user_3->lastName = 'Doe';


$persons = [
    $user_1,
    $user_2,
    $user_3
];

$result = array_column($persons, 'firstName' , 'id');

This will output:

Array
(
    [101010] => Sally
    [202020] => John
    [303030] => Peter
)